Implant with drug coating

ABSTRACT

Surgical methods and related medical devices for treating glaucoma are disclosed. The method comprises trabecular bypass surgery, which involve bypassing diseased trabecular meshwork with the use of a seton implant. The seton implant is used to prevent a healing process known as filling in, which has a tendency to close surgically created openings in the trabecular meshwork. The surgical method and novel implant are addressed to the trabecular meshwork, which is a major site of resistance to outflow in glaucoma. In addition to bypassing the diseased trabecular meshwork at the level of the trabecular meshwork, existing outflow pathways are also used or restored. The seton implant is positioned through the trabecular meshwork so that an inlet end of the seton implant is exposed to the anterior chamber of the eye and an outlet end is positioned into fluid collection channels at about an exterior surface of the trabecular meshwork or up to the level of aqueous veins.

CLAIM OF PRIORITY AND RELATED APPLICATIONS

[0001] This patent application is a continuation application of U.S.patent application Ser. No. 09/549,350, filed Apr. 14, 2000, which isincorporated in its entirety by reference herein. This application isalso related to U.S. patent application Ser. No. 10/309,711, filed Dec.4, 2002, and to three new U.S. patent applications filed on even dateherewith entitled “L-Shaped Stent with Bi-Directional Flow,” “Stent withAnchor,” and “Stent with a Micropump,” all of which are incorporated intheir entirety by reference herein.

FIELD OF THE INVENTION

[0002] The present invention generally relates to improved medicaldevices and methods for the reduction of elevated pressure in organs ofthe human body. More particularly, the present invention relates to thetreatment of glaucoma by trabecular bypass surgery, which is a means forusing an implant or seton, such as a micro stent, shunt or the like, tobypass diseased trabecular meshwork at the level of trabecular meshworkand use/restore existing outflow pathways.

BACKGROUND OF THE INVENTION

[0003] About two percent of people in the United States have glaucoma.Glaucoma is a group of eye diseases that causes pathological changes inthe optic disk and corresponding visual field loss resulting inblindness if untreated. Intraocular pressure elevation is the majoretiologic factor in all glaucomas.

[0004] In glaucomas associated with an elevation in eye pressure thesource of resistance to outflow is in the trabecular meshwork. Thetissue of the trabecular meshwork allows the “aqueous” to enterSchlemm's canal, which then empties into aqueous collector channels inthe posterior wall of Schlemm's canal and then into aqueous veins. Theaqueous or aqueous humor is a transparent liquid that fills the regionbetween the cornea at the front of the eye and the lens. The aqueoushumor is constantly secreted by the ciliary body around the lens, sothere is a continuous flow of the aqueous humor from the ciliary body tothe eye's front chamber. The eye's pressure is determined by a balancebetween the production of aqueous and its exit through the trabecularmeshwork (major route) or via uveal scleral outflow (minor route). Thetrabecular meshwork is located between the outer rim of the iris and theinternal periphery of the cornea. The portion of the trabecular meshworkadjacent to Schlemm's canal causes most of the resistance to aqueousoutflow Ouxtacanilicular meshwork).

[0005] Glaucoma is grossly classified into two categories: closed-angleglaucoma and open-angle glaucoma. The closed-angle glaucoma is caused byclosure of the anterior angle by contact between the iris and the innersurface of the trabecular meshwork. Closure of this anatomical angleprevents normal drainage of aqueous humor from the anterior chamber ofthe eye. Open-angle glaucoma is any glaucoma in which the angle of theanterior chamber remains open, but the exit of aqueous through thetrabecular meshwork is diminished. The exact cause for diminishedfiltration is unknown for most cases of open-angle glaucoma. However,there are secondary open-angle glaucomas which may include edema orswelling of the trabecular spaces (from steroid use), abnormal pigmentdispersion, or diseases such as hyperthyroidism that produce vascularcongestion.

[0006] All current therapies for glaucoma are directed at decreasingintraocular pressure. This is initially by medical therapy with drops orpills that reduce the production of aqueous humor or increase theoutflow of aqueous. However, these various drug therapies for glaucomaare sometimes associated with significant side effects, such asheadache, blurred vision, allergic reactions, death from cardiopulmonarycomplications and potential interactions with other drugs. When the drugtherapy fails, surgical therapy is used. Surgical therapy for open-angleglaucoma consists of laser (trabeculoplasty), trabeculectomy and aqueousshunting implants after failure of trabeculectomy or if trabeculectomyis unlikely to succeed. Trabeculectomy is a major surgery which is mostwidely used and is augmented with topically applied anticancer drugssuch as 5-flurouracil or mitomycin-c to decrease scarring and increasesurgical success.

[0007] Approximately 100,000 trabeculectomies are performed on Medicareage patients per year in the United States. This number would increaseif the morbidity associated with trabeculectomy could be decreased. Thecurrent morbidity associated with trabeculectomy consists of failure(10-15%), infection (a life long risk about 2-5%), choroidal hemorrhage(1%, a severe internal hemorrhage from pressure too low resulting invisual loss), cataract formation, and hypotony maculopathy (potentiallyreversible visual loss from pressure too low).

[0008] If it were possible to bypass the local resistance to outflow ofaqueous at the point of the resistance and use existing outflowmechanisms, surgical morbidity would greatly decrease. The reason forthis is that the episcleral aqueous veins have a backpressure that wouldprevent the eye pressure from going too low. This would virtuallyeliminate the risk of hypotony maculopathy and choroidal hemorrhage.Furthermore, visual recovery would be very rapid and risk of infectionwould be very small (a reduction from 2-5% to 0.05%). Because of thesereasons surgeons have tried for decades to develop a workable surgeryfor the trabecular meshwork.

[0009] The previous techniques, which have been tried, aregoniotomy/trabeculotomy, and other mechanical disruption of thetrabecular meshwork, such as trabeculopuncture, goniophotoablation,laser trabecular ablation and goniocurretage. They are briefly describedbelow.

[0010] Goniotomy/Trabeculotomy: Goniotomy and trabeculotomy are simpleand directed techniques of microsurgical dissection with mechanicaldisruption of the trabecular meshwork. These initially had earlyfavorable responses in the treatment of open-angle glaucoma. However,long-term review of surgical results showed only limited success inadults. In retrospect, these procedures probably failed secondary torepair mechanisms and a process of “filling in”. The filling in is theresult of a healing process which has the detrimental effect ofcollapsing and closing in of the created opening throughout thetrabecular meshwork. Once the created openings close, the pressurebuilds back up and the surgery fails.

[0011] Trabeculopuncture: Q-switched Neodymiun (Nd):YAG lasers also havebeen investigated as an optically invasive technique for creatingfull-thickness holes in trabecular meshwork. However, the relativelysmall hole created by this trabeculopuncture technique exhibits afilling in effect and fails.

[0012] Goniophotoablation/Laser Trabecular Ablation: Goniophotoablationis disclosed by Berlin in U.S. Pat. No. 4,846,172, and describes the useof an excimer laser to treat glaucoma by ablating the trabecularmeshwork. This was not demonstrated by clinical trial to succeed. Hillet al. used an Erbium:YAG laser to create full thickness holes throughtrabecular meshwork (Hill et al., Lasers in Surgery and Medicine11:341-346, 1991). This technique was investigated in a primate modeland a limited human clinical trial at the University of California,Irvine. Although morbidity was zero in both trials, success rates didnot warrant further human trials. Failure again was from filling in ofcreated defects in trabecular meshwork by repair mechanisms. Neither ofthese is a valid surgical technique for the treatment of glaucoma.

[0013] Goniocurretage: This is an ab-interno (from the inside)mechanical disruptive technique. This uses an instrument similar to acyclodialysis spatula with a microcurrette at the tip. Initial resultsare similar to trabeculotomy that fails secondary to repair mechanismsand a process of filling in.

[0014] Although trabeculectomy is the most commonly performed filteringsurgery, Viscocanulostomy (VC) and non-penetrating trabeculectomy (NPT)are two new variations of filtering surgery. These are ab-externo (fromthe outside), major ocular procedures in which Schlemm's canal issurgically exposed by making a large and very deep scleral flap. In theVC procedure, Schlemm's canal is canulated and viscoelastic substanceinjected (which dilates Schlemm's canal and the aqueous collectorchannels). In the NPT procedure, the inner wall of Schlemm's canal isstripped off after surgically exposing the canal.

[0015] Trabeculectomy, VC, and NPT are performed under a conjunctivaland scleral flap, such that the aqueous humor is drained onto thesurface of the eye or into the tissues located within the lateral wallof the eye. Normal physiological outflows are not used. These surgicaloperations are major procedures with significant ocular morbidity. WhenTrabeculectomy, VC, and NPT are thought to have a low chance forsuccess, a number of implantable drainage devices have been used toensure that the desired filtration and outflow of aqueous humor throughthe surgical opening will continue. The risk of placing a glaucomadrainage implant also includes hemorrhage, infection and postoperativedouble vision that is a complication unique to drainage implants.

[0016] Examples of implantable shunts or devices for maintaining anopening for the release of aqueous humor from the anterior chamber ofthe eye to the sclera or space underneath conjunctiva have beendisclosed in U.S. Pat. No. 6,007,511 (Prywes), U.S. Pat. No. 6,007,510(Nigam), U.S. Pat. No. 5,893,837 (Eagles et al.), U.S. Pat. No.5,882,327 (Jacob), U.S. Pat. No. 5,879,319 (Pynson et al.), U.S. Pat.No. 5,807,302 (Wandel), U.S. Pat. No. ,5752,928 (de Roulhac et al.),U.S. Pat. No. 5,743,868 (Brown et al.), U.S. Pat. No. 5,704,907(Nordquist et al.), U.S. Pat. No. 5,626,559 (Solomon), U.S. Pat. No.5,626,558 (Suson), U.S. Pat. No. 5,601,094 (Reiss), RE. U.S. Pat. No.35,390 (Smith), U.S. Pat. No. 5,558,630 (Fisher), U.S. Pat. No.5,558,629 (Baerveldt et al.), U.S. Pat. No. 5,520,631 (Nordquist etal.), U.S. Pat. No. 5,476,445 (Baerveldt et al.), U.S. Pat. No.5,454,796 (Krupin), U.S. Pat. No. 5,433,701 (Rubinstein), U.S. Pat. No.5,397,300 (Baerveldt et al.), U.S. Pat. No. 5,372,577 (Ungerleider),U.S. Pat. No. 5,370,607 (Memmen), U.S. Pat. No. 5,338,291 (Speckman etal.), U.S. Pat. No. 5,300,020 (L'Esperance, Jr.), U.S. Pat. No.5,178,604 (Baerveldt et al.), U.S. Pat. No. 5,171,213 (Price, Jr.), U.S.Pat. No. 5,041,081 (Odrich), U.S. Pat. No. 4,968,296 (Ritch et al.),U.S. Pat. No. 4,936,825 (Ungerleider), U.S. Pat. No. 4,886,488 (White),U.S. Pat. No. 4,750,901 (Molteno), U.S. Pat. No. 4,634,418 (Binder),U.S. Pat. No. 4,604,087 (Joseph), U.S. Pat. No. 4,554,918 (White), U.S.Pat. No. 4,521,210 (Wong), U.S. Pat. No. 4,428,746 (Mendez), U.S. Pat.No. 4,402,681 (Haas et al.), U.S. Pat. No. 4,175,563 (Arenberg et al.),and U.S. Pat. No. 4,037,604 (Newkirk).

[0017] All of the above embodiments and variations thereof have numerousdisadvantages and moderate success rates. They involve substantialtrauma to the eye and require great surgical skill by creating a holeover the full thickness of the sclera/comea into the subconjunctivalspace. Furthermore, normal physiological outflow pathways are not used.The procedures are mostly performed in an operating room generating afacility fee, anesthesiologist's professional fee and have a prolongedrecovery time for vision. The complications of filtration surgery haveinspired ophthalmic surgeons to look at other approaches to loweringintraocular pressure.

[0018] The trabecular meshwork and juxtacanilicular tissue togetherprovide the majority of resistance to the outflow of aqueous and, assuch, are logical targets for surgical removal in the treatment ofopen-angle glaucoma. In addition, minimal amounts of tissue are alteredand existing physiologic outflow pathways are utilized. Trabecularbypass surgery has the potential for much lower risks of choroidalhemorrhage, infection and uses existing physiologic outflow mechanisms.This surgery could be performed under topical anesthesia in aphysician's office with rapid visual recovery.

[0019] Therefore, there is a great clinical need for the treatment ofglaucoma by a method that would be faster, safer and less expensive thancurrently available modalities. Trabecular bypass surgery is aninnovative surgery which uses a micro stent, shunt, or other implant tobypass diseased trabecular meshwork alone at the level of trabecularmeshwork and use or restore existing outflow pathways. The object of thepresent invention is to provide a means and methods for treatingelevated intraocular pressure in a manner which is simple, effective,disease site specific and can be performed on an outpatient basis.

SUMMARY OF THE INVENTION

[0020] In some preferred embodiments, the seton has an inlet portionconfigured to extend through a portion of the trabecular meshwork of aneye, and an outlet portion configured to extend into Schlemm's canal ofthe eye, wherein the inlet portion is disposed at an angle relative tothe outlet portion. In some embodiments, the outlet portion has a lumenwith an oval cross-section having a long axis.

[0021] The outlet portion in certain embodiments has a longitudinalaxis, such that the long axis of the oval cross-section and thelongitudinal axis of the outlet portion define a plane, the inletportion having a longitudinal axis which lies outside the plane at anangle θ (theta) thereto.

[0022] In some preferred arrangements, the seton comprises an inletportion, configured to extend through a portion of the trabecularmeshwork; an outlet portion, configured to extend into Schlemm's canal;and at least one protrusion on the outlet portion, configured to exerttraction against an inner surface of Schlemm's canal. This protrusioncan comprise at least one barb or ridge.

[0023] Some preferred embodiments comprise an inlet portion configuredto extend through a portion of the trabecular meshwork, an outletportion configured to extend into Schlemm's canal, and a one-way valvewithin the inlet and/or outlet portions.

[0024] A method for delivering a seton within an eye is disclosed,comprising providing an elongate guide member, advancing a distal end ofthe guide member through at least a portion of the trabecular meshworkof the eye, advancing the seton along the guide member toward the distalend, and positioning the seton to conduct aqueous humor between theanterior chamber of the eye and Schlemm's canal.

[0025] In certain embodiments, the advancing of the guide membercomprises advancing it from the anterior chamber into the trabecularmeshwork. In further embodiments, the positioning comprises positioningan end of the seton within Schlemm's canal adjacent to an aqueouscollection channel.

[0026] Certain preferred embodiments include an apparatus for deliveringa seton to the anterior chamber of an eye comprising an elongate tubehaving a lumen, an outer surface, and a distal end; a removable,elongate guide member within the lumen, configured to permit the setonto be advanced and to be positioned in the trabecular meshwork of theeye. This apparatus can further comprise a cutting member positioned atthe distal end of the tube. The cutting member can be selected from thegroup consisting of a knife, a laser probe, a pointed guide member, asharpened distal end of said tube, and an ultrasonic cutter. Theapparatus can also further comprise an opening in the outer surface ofthe tube, configured to allow fluid infusion into the eye.

[0027] In further preferred embodiments, an apparatus for delivering aseton in an eye, comprises an elongate member adapted for insertion intoan anterior chamber of the eye, the elongate member having a distal endportion configured to retain the seton therein, the distal end portioncomprising a cutting member configured to form an opening in thetrabecular meshwork of the eye for receipt of the seton, such that oneend of the seton is in Schlemm's canal. The elongate member can furthercomprise a lumen which conducts fluid toward said distal end portion.

[0028] The preferred embodiment provides further surgical treatment ofglaucoma (trabecular bypass surgery) at the level of trabecular meshworkand restores existing physiological outflow pathways. An implantbypasses diseased trabecular meshwork at the level of trabecularmeshwork and which restores existing physiological outflow pathways. Theimplant has an inlet end, an outlet end and a lumen therebetween. Theinlet is positioned in the anterior chamber at the level of the internaltrabecular meshwork and the outlet end is positioned at about theexterior surface of the diseased trabecular meshwork and/or into fluidcollection channels of the existing outflow pathways.

[0029] In accordance with a preferred method, trabecular bypass surgerycreates an opening or a hole through the diseased trabecular meshworkthrough minor microsurgery. To prevent “filling in” of the hole, abiocompatible elongated implant is placed within the hole as a seton,which may include, for example, a solid rod or hollow tube. In oneexemplary embodiment, the seton implant may be positioned across thediseased trabecular meshwork alone and it does not extend into the eyewall or sclera. In another embodiment, the inlet end of the implant isexposed to the anterior chamber of the eye while the outlet end ispositioned at the exterior surface of the trabecular meshwork. Inanother exemplary embodiment, the outlet end is positioned at and overthe exterior surface of the trabecular meshwork and into the fluidcollection channels of the existing outflow pathways. In still anotherembodiment, the outlet end is positioned in the Schlemm's canal. In analternative embodiment, the outlet end enters into fluid collectionchannels up to the level of the aqueous veins with the seton inserted ina retrograde or antegrade fashion.

[0030] According to the preferred embodiment, the seton implant is madeof biocompatible material, which is either hollow to allow the flow ofaqueous humor or solid biocompatible material that imbibes aqueous. Thematerial for the seton may be selected from the group consisting ofporous material, semi-rigid material, soft material, hydrophilicmaterial, hydrophobic material, hydrogel, elastic material, and thelike.

[0031] In further accordance with the preferred embodiment, the setonimplant may be rigid or it may be made of relatively soft material andis somewhat curved at its distal section to fit into the existingphysiological outflow pathways, such as Schlemm's canal. The distalsection inside the outflow pathways may have an oval shape to stabilizethe seton in place without undue suturing. Stabilization or retention ofthe seton may be further strengthened by a taper end and/or by at leastone ridge or rib on the exterior surface of the distal section of theseton, or other surface alterations designed to retain the seton.

[0032] In one embodiment, the seton may include a micropump, one wayvalve, or semi-permeable membrane if reflux of red blood cells or serumprotein becomes a clinical problem. It may also be useful to use abiocompatible material that hydrates and expands after implantation sothat the seton is locked into position around the trabecular meshworkopening or around the distal section of the seton.

[0033] One of the advantages of trabecular bypass surgery, as disclosedherein, and the use of a seton implant to bypass diseased trabecularmeshwork at the level of trabecular meshwork and thereby use existingoutflow pathways is that the treatment of glaucoma is substantiallysimpler than in existing therapies. A further advantage of the inventionis the utilization of simple microsurgery that may be performed on anoutpatient basis with rapid visual recovery and greatly decreasedmorbidity. Finally, a distinctly different approach is used than isfound in existing implants. Physiological outflow re used orre-established by the implant of the present invention, in n withpreviously disclosed methodologies.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Additional objects and features of the present invention willbecome more apparent and the invention itself will be best understoodfrom the following Detailed Description of Exemplary Embodiments, whenread with reference to the accompanying drawings.

[0035]FIG. 1 is a sectional view of an eye for illustration purposes.

[0036]FIG. 2 is a close-up sectional view, showing the anatomicaldiagram of trabecular meshwork and the anterior chamber of the eye.

[0037]FIG. 3 is an embodiment of the seton implant constructed accordingto the principles of the invention.

[0038]FIG. 4 is a top cross-sectional view of section 1-1 of FIG. 3.

[0039]FIG. 5 is another embodiment of the seton implant constructed inaccordance with the principles of the invention.

[0040]FIG. 6 is a perspective view illustrating the seton implant of thepresent invention positioned within the tissue of an eye.

[0041]FIG. 7 is an alternate exemplary method for placing a setonimplant at the implant site.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0042] Referring to FIGS. 1 to 7, what is shown is a method for thetreatment of glaucoma by trabecular bypass surgery. In particular, aseton implant is used to bypass diseased trabecular meshwork at thelevel of trabecular meshwork to use or restore existing outflow pathwaysand methods thereof.

[0043] For background illustration purposes, FIG. 1 shows a sectionalview of an eye 10, while FIG. 2 shows a close-up view, showing therelative anatomical locations of the trabecular meshwork, the anteriorchamber, and Schlernm's canal. Thick collagenous tissue known as sclera11 covers the entire eye 10 except that portion covered by the cornea12. The cornea 12 is a thin transparent tissue that focuses andtransmits light into the eye and the pupil 14 which is the circular holein the center of the iris 13 (colored portion of the eye). The cornea 12merges into the sclera 11 at a juncture referred to as the limbus 15.The ciliary body 16 begins internally in the eye and extends along theinterior of the sclera 11 and becomes the choroid 17. The choroid 17 isa vascular layer of the eye underlying retina 18. The optic nerve 19transmits visual information to the brain and is sequentially destroyedby glaucoma.

[0044] The anterior chamber 20 of the eye 10, which is bound anteriorlyby the cornea 12 and posteriorly by the iris 13 and lens 26, is filledwith aqueous. Aqueous is produced primarily by the ciliary body 16 andreaches the anterior chamber angle 25 formed between the iris 13 and thecornea 12 through the pupil 14. In a normal eye, the aqueous is removedthrough the trabecular meshwork 21. Aqueous passes through trabecularmeshwork 21 into Schlemm's canal 22 and through the aqueous veins 23which merge with blood-carrying veins and into venous circulation.Intraocular pressure of the eye 10 is maintained by the intricatebalance of secretion and outflow of the aqueous in the manner describedabove. Glaucoma is characterized by the excessive buildup of aqueousfluid in the anterior chamber 20 which produces an increase inintraocular pressure (fluids are relatively incompressible and pressureis directed equally to all areas of the eye).

[0045] As shown in FIG. 2, the trabecular meshwork 21 constitutes asmall portion of the sclera 11. It is understandable that creating ahole or opening for implanting a device through the tissues of theconjunctiva 24 and sclera 11 is relatively a major surgery as comparedto a surgery for implanting a device through the trabecular meshwork 21only. A seton implant 31 of the present invention for either using orrestoring existing outflow pathways positioned through the trabecularmeshwork 21 is illustrated in FIG. 5.

[0046] In a first embodiment, a method for increasing aqueous humoroutflow in an eye of a patient to reduce the intraocular pressuretherein. The method comprises bypassing diseased trabecular meshwork atthe level of the trabecular meshwork and thereby restoring existingoutflow pathways. Alternately, a method for increasing aqueous humoroutflow in an eye of a patient to reduce an intraocular pressure thereinis disclosed. The method comprises bypassing diseased trabecularmeshwork at a level of said trabecular meshwork with a seton implant andusing existing outflow pathways. The seton implant 31 may be anelongated seton or other appropriate shape, size or configuration. Inone embodiment of an elongated seton implant, the seton has an inletend, an outlet end and a lumen therebetween, wherein the inlet end ispositioned at an anterior chamber of the eye and the outlet end ispositioned at about an exterior surface of said diseased trabecularmeshwork. Furthermore, the outlet end may be positioned into fluidcollection channels of the existing outflow pathways. Optionally, theexisting outflow pathways may comprise Schlemm's canal 22. The outletend may be further positioned into fluid collection channels up to thelevel of the aqueous veins with the seton inserted either in aretrograde or antegrade fashion with respect to the existing outflowpathways.

[0047] In a further alternate embodiment, a method is disclosed forincreasing aqueous humor outflow in an eye of a patient to reduce anintraocular pressure therein. The method comprises (a) creating anopening in trabecular meshwork, wherein the trabecular meshworkcomprises an interior side and exterior side; (b) inserting a setonimplant into the opening; and (c) transporting the aqueous humor by saidseton implant to bypass the trabecular meshwork at the level of saidtrabecular meshwork from the interior side to the exterior side of thetrabecular meshwork.

[0048]FIG. 3 shows an embodiment of the seton implant 31 constructedaccording to the principles of the invention. The seton implant maycomprise a biocompatible material, such as a medical grade silicone, forexample, the material sold under the trademark Silastic™, which isavailable from Dow Corning Corporation of Midland, Mich., orpolyurethane, which is sold under the trademark Pellethane™, which isalso available from Dow Corning Corporation. In an alternate embodiment,other biocompatible materials (biomaterials) may be used, such aspolyvinyl alcohol, polyvinyl pyrolidone, collagen, heparinized collagen,tetrafluoroethylene, fluorinated polymer, fluorinated elastomer,flexible fused silica, polyolefin, polyester, polysilison, mixture ofbiocompatible materials, and the like. In a further alternateembodiment, a composite biocompatible material by surface coating theabove-mentioned biomaterial may be used, wherein the coating materialmay be selected from the group consisting of polytetrafluoroethlyene(PTFE), polyimide, hydrogel, heparin, therapeutic drugs, and the like.

[0049] The main purpose of the seton implant is to assist infacilitating the outflow of aqueous in an outward direction 40 into theSchlemm's canal and subsequently into the aqueous collectors and theaqueous veins so that the intraocular pressure is balanced. In oneembodiment, the seton implant 31 comprises an elongated tubular elementhaving a distal section 32 and an inlet section 44. A rigid or flexibledistal section 32 is positioned inside one of the existing outflowpathways. The distal section may have either a tapered outlet end 33 orhave at least one ridge 37 or other retention device protruding radiallyoutwardly for stabilizing the seton implant inside said existing outflowpathways after implantation. For stabilization purposes, the outersurface of the distal section 32 may comprise a stubbed surface, aribbed surface, a surface with pillars, a textured surface, or the like.The outer surface 36, including the outer region 35 and inner region 34at the outlet end 33, of the seton implant is biocompatible and tissuecompatible so that the interaction/irritation between the outer surfaceand the surrounding tissue is minimized. The seton implant may compriseat least one opening at a location proximal the distal section 32, awayfrom the outlet end 33, to allow flow of aqueous in more than onedirection. The at least one opening may be located on the distal section32 at about opposite of the outlet end 33.

[0050] In another exemplary embodiment, the seton implant 31 may have aone-way flow controlling means 39 for allowing one-way aqueous flow 40.The one-way flow controlling means 39 may be selected from the groupconsisting of a check valve, a slit valve, a micropump, a semi-permeablemembrane, or the like. To enhance the outflow efficiency, at least oneoptional opening 41 in the proximal portion of the distal section 32, ata location away from the outlet end 33, and in an exemplary embodimentat the opposite end of the outlet end 33, is provided.

[0051]FIG. 4 shows a top cross-sectional view of FIG. 3. The shape ofthe opening of the outlet end 33 and the remaining body of the distalsection 32 may be oval, round or some other shape adapted to conform tothe shape of the existing outflow pathways. This configuration willmatch the contour of Schlemm's canal to stabilize the inlet section withrespect to the iris and cornea by preventing rotation.

[0052] As shown in FIG. 3, the seton implant of the present inventionmay have a length between about 0.5 mm to over a meter, depending on thebody cavity the seton implant applies to. The outside diameter of theseton implant may range from about 30 μm to about 500 μm. The lumendiameter is preferably in the range between about 20 μm to about 150 μm.The seton implant may have a plurality of lumens to facilitate multipleflow transportation. The distal section may be curved at an anglebetween about 30 degrees to about 150 degrees, in an exemplaryembodiment at around 70-110 degrees, with reference to the inlet section44.

[0053]FIG. 5 shows another embodiment of the seton implant 45constructed in accordance with the principles of the invention. In anexemplary embodiment, the seton implant 45 may comprise at least twosections: an inlet section 47 and an outlet section 46. The outletsection has an outlet opening 48 that is at the outlet end of the setonimplant 45. The shape of the outlet opening 48 is preferably an ovalshape to conform to the contour of the existing outflow pathways. Aportion of the inlet section 47 adjacent the joint region to the outletsection 46 will be positioned essentially through the diseasedtrabecular meshwork while the remainder of the inlet section 47 and theoutlet section 46 are outside the trabecular meshwork. As shown in FIG.5, the long axis of the oval shape opening 48 lies in a first planeformed by an X-axis and a Y-axis. To better conform to the anatomicalcontour of the anterior chamber 20, the trabecular meshwork 21 and theexisting outflow pathways, the inlet section 47 may preferably lie at anelevated second plane, at an angle θ, from the first plane formed by animaginary inlet section 47A and the outlet section 46. The angle θ maybe between about 30 degrees and about 150 degrees.

[0054]FIG. 6 shows a perspective view illustrating the seton implant 31,45 of the present invention positioned within the tissue of an eye 10. Ahole/opening is created through the diseased trabecular meshwork 21. Thedistal section 32 of the seton implant 31 is inserted into the hole,wherein the inlet end 38 is exposed to the anterior chamber 20 while theoutlet end 33 is positioned at about an exterior surface 43 of saiddiseased trabecular meshwork 21. In a further embodiment, the outlet end33 may further enter into fluid collection channels of the existingoutflow pathways.

[0055] In one embodiment, the means for forming a hole/opening in thetrabecular mesh 21 may comprise an incision with a microknife, anincision by a pointed guidewire, a sharpened applicator, a screw shapedapplicator, an irrigating applicator, or a barbed applicator.Alternatively, the trabecular meshwork may be dissected off with aninstrument similar to a retinal pick or microcurrette. The opening mayalternately be created by retrogade fiberoptic laser ablation.

[0056]FIG. 7 shows an illustrative method for placing a seton implant atthe implant site. An irrigating knife or applicator 51 comprises asyringe portion 54 and a cannula portion 55. The distal section of thecannula portion 55 has at least one irrigating hole 53 and a distalspace 56 for holding a seton implant 31. The proximal end 57 of thelumen of the distal space 56 is sealed from the remaining lumen of thecannula portion 55.

[0057] For positioning the seton 31 in the hole or opening through thetrabecular meshwork, the seton may be advanced over the guidewire or afiberoptic (retrograde). In another embodiment, the seton is directlyplaced on the delivery applicator and advanced to the implant site,wherein the delivery applicator holds the seton securely during thedelivery stage and releases it during the deployment stage.

[0058] In an exemplary embodiment of the trabecular meshwork surgery,the patient is placed in the supine position, prepped, draped andanesthesia obtained. In one embodiment, a small (less than 1 mm) selfsealing incision is made. Through the cornea opposite the setonplacement site, an incision is made in trabecular meshwork with anirrigating knife. The seton 31 is then advanced through the corneaincision 52 across the anterior chamber 20 held in an irrigatingapplicator 51 under gonioscopic (lens) or endoscopic guidance. Theapplicator is withdrawn and the surgery concluded. The irrigating knifemay be within a size range of 20 to 40 gauges, preferably about 30gauge.

[0059] From the foregoing description, it should now be appreciated thata novel approach for the surgical treatment of glaucoma has beendisclosed for releasing excessive intraocular pressure. While theinvention has been described with reference to a specific embodiment,the description is illustrative of the invention and is not to beconstrued as limiting the invention. Various modifications andapplications may occur to those who are skilled in the art, withoutdeparting from the true spirit and scope of the invention, as describedby the appended claims.

What is claimed is:
 1. An implant for treating glaucoma, comprising: abody comprised of material which includes a drug, said body having aninlet portion and an outlet portion, said inlet portion configured totransport fluid from the anterior chamber to the outlet portion when theoutlet portion is disposed in Schlemm's canal, said outlet portionhaving an outflow opening.
 2. The implant of claim 1, wherein said bodyis coated with said drug.
 3. The implant of claim 1, wherein said drugcomprises heparin.